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ORC-2011: [C++] Fix Timezone to support legacy US TimeZone identifiers #2422

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ORC-2011: [C++] Fix Timezone to support legacy US TimeZone identifiers #2422

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43 changes: 34 additions & 9 deletions c++/src/Timezone.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -33,8 +33,24 @@ namespace orc {
// default location of the timezone files
static const char DEFAULT_TZDIR[] = "/usr/share/zoneinfo";

// location of a symlink to the local timezone
static const char LOCAL_TIMEZONE[] = "/etc/localtime";
// location of a symlink to the local timezone is /etc/localtime
static const char LOCAL_TIMEZONE_DIR[] = "/etc";
static const char LOCAL_TIMEZONE[] = "localtime";

// US aliases from https://data.iana.org/time-zones/tzdb/backward
static const std::map<const std::string, const std::string> TZ_ALIASES = {
{"US/Alaska", "America/Anchorage"},
{"US/Aleutian", "America/Adak"},
{"US/Arizona", "America/Phoenix"},
{"US/Central", "America/Chicago"},
{"US/East-Indiana", "America/Indiana/Indianapolis"},
{"US/Eastern", "America/New_York"},
{"US/Hawaii", "Pacific/Honolulu"},
{"US/Indiana-Starke", "America/Indiana/Knox"},
{"US/Michigan", "America/Detroit"},
{"US/Mountain", "America/Denver"},
{"US/Pacific", "America/Los_Angeles"},
{"US/Samoa", "Pacific/Pago_Pago"}};

enum TransitionKind { TRANSITION_JULIAN, TRANSITION_DAY, TRANSITION_MONTH };

Expand Down Expand Up @@ -734,14 +750,26 @@ namespace orc {
* Get a timezone by absolute filename.
* Results are cached.
*/
const Timezone& getTimezoneByFilename(const std::string& filename) {
const Timezone& getTimezoneByFilename(const std::string& dir, const std::string& zone) {
std::string filename(dir);
filename += "/";
filename += zone;
// ORC-110
std::lock_guard<std::mutex> timezone_lock(timezone_mutex);
std::map<std::string, std::shared_ptr<Timezone> >::iterator itr = timezoneCache.find(filename);
if (itr != timezoneCache.end()) {
return *(itr->second).get();
}
timezoneCache[filename] = std::make_shared<LazyTimezone>(filename);
auto it = TZ_ALIASES.find(zone);
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@dongjoon-hyun dongjoon-hyun Sep 27, 2025

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This overhead occurs once per zone because we fill timezoneCache only one time and reuse it forever.

if (it == TZ_ALIASES.end()) {
timezoneCache[filename] = std::make_shared<LazyTimezone>(filename);
} else {
std::string newfilename(dir);
newfilename += "/";
newfilename += it->second;
timezoneCache[newfilename] = std::make_shared<LazyTimezone>(newfilename);
timezoneCache[filename] = timezoneCache[newfilename];
}
return *timezoneCache[filename].get();
}

Expand All @@ -752,7 +780,7 @@ namespace orc {
#ifdef _MSC_VER
return getTimezoneByName("UTC");
#else
return getTimezoneByFilename(LOCAL_TIMEZONE);
return getTimezoneByFilename(LOCAL_TIMEZONE_DIR, LOCAL_TIMEZONE);
#endif
}

Expand All @@ -761,10 +789,7 @@ namespace orc {
* Results are cached.
*/
const Timezone& getTimezoneByName(const std::string& zone) {
std::string filename(getTimezoneDirectory());
filename += "/";
filename += zone;
return getTimezoneByFilename(filename);
return getTimezoneByFilename(getTimezoneDirectory(), zone);
}

/**
Expand Down
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